The present invention relates to a brushless electric signal transmission apparatus capable of effecting electric signal transfer between a stationary member and a rotary member, and more particularly, to this kind of an apparatus which is easy to assemble.
A brushless electric signal transmission apparatus has been used for electrically connecting a steering wheel and a steering column of the automobile, for instance. The brushless apparatus of this kind for the steering system allows a horn signal and an automatic driving signal to be transmitted from switches located at the steering wheel to a controller, etc. at the side of the vehicle body via the steering column, regardless of a rotary position of the steering wheel.
In the case of an automobile provided with an air bag system, moreover, the brushless apparatus is also used for electrically connecting a shock sensor and a diagnosis unit disposed on the vehicle body to an inflator of the air bag at the side of the steering wheel, regardless of a rotary position of the steering wheel.
The above-described apparatus comprises a stationary housing fixed to the steering column, a rotary housing fitted thereto and coupled to the steering wheel, i.e., a steering shaft, and a flat cable of an eddy or spiral form housed within a ring chamber located between the stationary housing and the rotary housing.
The respective terminal ends of conductors, which form the flat cable, at the side of the rotary housing are electrically connected to the switches and the inflator at the side of the steering wheel via flexible covered lead wires, while the terminal ends of these conductors at the side of the stationary housing are also electrically connected to the controller and the diagnosis unit via flexible covered lead wires.
When the above-described apparatus is assembled, each of the conductors of the flat cable is welded or soldered to its counterpart, i.e., a corresponding one of the covered lead wires, directly, or via a bus bar.
However, when the conductor and the covered lead wire are welded or soldered for mutual connection, since the latter is flexible, it is difficult to connect them, and further, since the lead wire is usually made of a strand, its cores are easy to come apart, which makes the connecting work difficult.